In some self-propelled snow removers, a snow-removing implement is attached to a machine body so as to be capable of lifting, lowering, and rolling, and a travel unit is provided to the machine body. The snow-removing implement is composed of an auger, for example. In a snow remover provided with an auger, a system is adopted whereby the height of the auger is varied according to snow removal circumstances. Elevating the lower surface of the auger when the snow remover is moving enables more efficient travel. On the other hand, lowering the lower surface of the auger during snow removal enables more efficient snow removal. Furthermore, it is often the case that the height of the auger is varied in conjunction with irregularities in the road surface during snow removal. Using human power to vary the height of the auger in this manner places a large burden on the operator.
Techniques for raising and lowering the auger by machine power have been proposed in order to lighten the burden on the operator. Such auger-type snow removers are described in Japanese Patent Laid-Open Publication No. 61-30085 and Japanese Utility Model Laid-Open Publication No. 61-11292.
In the auger-type snow remover described in the 61-30085 publication, the auger is raised and lowered by using an operating lever to operate a hydraulic cylinder for lifting, and the auger is rolled by using the operating lever to operate hydraulic cylinder for rolling.
In the auger-type snow remover described in the 61-11292 publication, an auger case is raised and lowered by a hydraulic cylinder for vertical movement, and the auger case is rolled by a horizontal-movement hydraulic cylinder. When the auger case is tilted to the left or right in relation to the road surface, the auger case is automatically rolled by the horizontal-movement hydraulic cylinder to correct the tilt.
During snow removal using these auger-type snow removers, the operator often turns the snow remover according to the snow removal situation. Because the snow removal operation is under way, the auger and auger housing are lowered to a point near the road surface. When the snow remover is turned in this state, accumulated snow interferes with turning depending on the state of snow accumulated around the snow remover. The auger must therefore be manually raised each time the operator turns the snow remover. Although the auger is lifted and lowered by machine power, there is potential for further improvement in order to further ease the burden placed on the operator.
There is therefore a need for a technique whereby the ability to turn the self-propelled snow remover during the snow removal operation is enhanced, and the burden placed on the operator is further reduced.